Terne electroplating bath



Patented Aug. 10, 1948 UNITED STATES PATENT OFFICE TERNE ELECTROPLATING BATH John S. Nachtman, Youngstown, Ohio No Drawing. Original application June 26, 1940, Serial No. 342,525, now Patent No. 2,370,986, dated March 6, 1945. Divided and this application March 2, 1945, Serial No. 580,729

1 Claim. 1

The invention relates to tame electroplating baths and more particularly to additions to be made to such baths with the object and efiectof obtaining a tin-lead or terne deposit of supenor quality. This application is a division of my prior copending application Serial No. 342,525, filed June 26, 1940, now Patent 'No. 2,370,986, March 6, 1945.

I have discovered that nicotine, either alone or in association with Duponol 80, is a most efiective addition agent afiording marked improvement in the quality of electrolytically deposited coatings of the lead-tin alloy of tame-plate; and that a teme plating bath containing nicotine is serviceable in the plating of steel strip, sheet and wire. Such use of nicotine I believe to be wholly new.

Those familiar with the art realize that addition agents are necessary in Platin V riou metals, to obtain fine-grained, heavy deposits, free from trees on the sharp edges or projections. The literature abounds with suggestions of the use of different addition agents in electroplating baths, agents such as gelatin, glue, peptone, beta-naphthol, cresol, sulfonated crescl, clove oil, gum arabic, tannic acid, 'dextrine, etc. Nicotine, however has never to my knowledge been suggested for use in a tame electroplating bath for obtaining a deposit of markedly im-- proved quality.

I have found that the use of nicotine in a terne electroplating bath has a very great effect in eliminating coarseness and treeing of the deposit. This is particularly true in making heavier deposits of the order of one-half to two ounces to the square foot of surface area. I also have found it desirable to use nicotine in a terne electroplating bath in association with addition agents such as a protein-type colloid, and, particularly in association with such a wetting agent as Duponol 80. I

The following is an example or a tame bath in which nicotine proved its worth as a satisfactory addition agent:

Grams per liter White lead 112.5 Stannous oxide 11.35 Boric acid 186.8 Hydrofiuori-c acid (30%) 650 Nicotine Beta-naphthol 2 The bath of the foregoing example may be operated at room temperature and at 25-150 amperes per square foot.

In the example given, the tin and lead salts named may be replaced by other inorganic or organic tin and lead salts. The acidity of the bath may be varied over a rather wide range; the degree of concentration, both of the tin and lead salts and of the addition agents, may be varied over a rather wide range; and the bath temperature may be varied-all to meet the various requirements of character of deposit, cost of solution, and current density.

The bath is operable with either soluble anodes of lead and tin or insoluble anodes such as carbon, and gives dense, fine-grained deposits, suitable as coatings upon steel, or upon other conductors, metallic or non-metallic. Likewise, the deposit is adherent and covers well.

It is to be understood that I am not limiting myself in the use of the various ingredients to the concentrations given in the example. The material referred to herein as Duponol is the sodium salt of the sulfate ester of a mixture of allphatic alcohols in which the Ca chain-length predominates.

Accordingly, I have discovered that nicotine is a very valuable addition agent in plating the leadtin alloy of terne-plate from an electroplating bath to replace the protein-type colloids such as gelatin, glue or peptone, commonly used in electrolytic baths. The terne electroplating bath of the present invention containing nicotine has a long operating life, does not form any gummy precipitate, and does not form any sludge with the salts of the bath.

I claim:

A terne electroplating bath formed from the following components substantially in the ratios set out: white lead-112.5 g./l., stannous oxide- 11.35 g./l., boric acid-486.8 g./l., hydrofluoric acid (30%)650 g./l., nic0tine-10 g./l., and beta-naphthol2 g. /l.

JOHN S. NACHTMAN.

REFERENCES CITED UNITED STATES PATENTS Name Date Colcord July 7, 1925 OTHER REFERENCES Trans. Electrochem. Soc., vol. 26 (1914), pages 117-128.

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